[zfs-discuss] ZFS, SSD mirror (without using whole disk)

Kash Pande kashpande at gmail.com
Sat Jan 16 11:33:07 EST 2016


It's ready for testing - and the author has asked that people do so.

https://github.com/zfsonlinux/zfs/pull/3656

On 16/01/16 07:53 AM, Tamas Papp via zfs-discuss wrote:
>
> fyi ZFS on *Linux* does not support trim yet.
>
> -- 
> Sent from mobile
>
> On January 16, 2016 13:42:48 fermulator via zfs-discuss 
> <zfs-discuss at list.zfsonlinux.org> wrote:
>
>> Hey all,
>>
>> I read here about ZFS's TRIM support on SSDs
>> http://www.open-zfs.org/wiki/Features#TRIM_Support
>>
>> What I'm wondering is if we have a non-whole-disk utilization of ZFS 
>> on mirror pool consisting of 2x SSDs, can ZFS still issue TRIM 
>> commands to the underlying device?
>> The SSDs are older, so I'm concerned about maintaining the health of 
>> the devices.
>>
>> For example, consider if we were running the root filesystem on ZFS 
>> mirror SSDs; this site does not currently discuss booting from 
>> whole-disk root volumes:
>> https://github.com/zfsonlinux/pkg-zfs/wiki/HOWTO-install-Ubuntu-14.04---15.04-to-a-Native-ZFS-Root-Filesystem
>> so, at the moment, I've setup my root volume with a sliver for boot, 
>> the rest for ZFS... bad idea?
>>
>> $ sudo zpool status
>>   pool: zfsmain
>>  state: ONLINE
>> status: Some supported features are not enabled on the pool. The pool can
>>     still be used, but some features are unavailable.
>> action: Enable all features using 'zpool upgrade'. Once this is done,
>>     the pool may no longer be accessible by software that does not 
>> support
>>     the features. See zpool-features(5) for details.
>>   scan: none requested
>> config:
>>
>> NAME STATE     READ WRITE CKSUM
>> zfsmain ONLINE       0     0     0
>> mirror-0 ONLINE       0     0     0
>> ata-KINGSTON_SNV425S264GB_07MA20034453-part1  ONLINE 0     0     0
>> ata-KINGSTON_SNV425S264GB_07MA20035331-part1  ONLINE 0     0     0
>>
>> errors: No known data errors
>>
>>   pool: zstorage
>>  state: ONLINE
>>   scan: none requested
>> config:
>>
>>     NAME STATE     READ WRITE CKSUM
>>     zstorage ONLINE       0     0     0
>>       mirror-0 ONLINE       0     0     0
>>         ata-WDC_WD6400AAKS-00A7B2_WD-WCASY7751034 ONLINE       0     
>> 0     0
>>         ata-WDC_WD6400AAKS-00A7B2_WD-WMASY5518479 ONLINE       0     
>> 0     0
>>
>> errors: No known data errors
>>
>> $ sudo gdisk /dev/disk/by-id/ata-KINGSTON_SNV425S264GB_07MA20034453
>> GPT fdisk (gdisk) version 0.8.8
>>
>> Partition table scan:
>>   MBR: protective
>>   BSD: not present
>>   APM: not present
>>   GPT: present
>>
>> Found valid GPT with protective MBR; using GPT.
>>
>> Command (? for help): p
>> Disk /dev/disk/by-id/ata-KINGSTON_SNV425S264GB_07MA20034453: 
>> 125045424 sectors, 59.6 GiB
>> Logical sector size: 512 bytes
>> Disk identifier (GUID): 4E92D2E6-B310-4EC9-9652-319DC6336612
>> Partition table holds up to 128 entries
>> First usable sector is 34, last usable sector is 125045390
>> Partitions will be aligned on 2048-sector boundaries
>> Total free space is 2669 sectors (1.3 MiB)
>>
>> Number  Start (sector)    End (sector)  Size Code  Name
>>    1            2048       125028351   59.6 GiB 8300  zfs
>>    2       125028352       125044735   8.0 MiB EF02  grub
>>
>> Command (? for help): q
>>
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